This is a simple PHP warning and not errors.
Do you have WP_DEBUG set to true in your wp-config.php file?
If you do then please set it to false.
This will hide the warning messages and you will be able to use your site normally.

Thank you very much for reporting the issue, and thank you @Vinod Dalvi for the suggested fix. The latest plugin release (v1.7.3, just released) should have this issue fixed. Can you please update and see if it helps?

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